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(No Model.) v I v V T. MURDOOK & J. L. L. KNOX.

METHOD OF AND MEANS FOR BLASTING OUT ROCK CORNERS. No. 357,730.

P d w m V n UNITED STATES THOMAS MU RDOCK, OF MIDDLETOl/VN,

PATENT. OFFICE.

CONNECTICUT, AND JOHN L. L. KNOX,

OF ALLEGHENY, PA., ASSIGNORS TO THE KNOX ROCK BLASTING COM- PANY, OF PITTSBURG, PENNSYLVANIA.

METHOD OF AND MEANS FOR BLASTING OUT ROCK CORNERS.

SPECIFICATION forming part of Letters Patent No. 357,730, dated February 15, 1887.

Application filed July 22, 1886.

To all whom it may concern.-

Be it known that we, THOMAS MURDOOK, of Middletown, in the county of Middlesex and State of Connecticut, and JOHN L. L. KNOX,

5 of Allegheny, in the county of Allegheny and State of Pennsylvania, have invented a certain new and useful Improvement in Means for and Method of Blasting Out Rock Corners, of which the following is a description, reference being had to the accompanying drawings,

where- Figure 1 is what may be called a side view of the lowerportion of the drill made use of, (considering the part next A the front,) the I drill being represented as being in a previously'drilled round hole in a rock and engaged in cutting a V-shaped groove in the wall of the rock. Fig. 2 is what may be called a front view of the lower portion of the same drill.

Fig. 3 is what may be called a rear view of the lower portion of the same drilL Fig. 4 is a view of the bottom or lower end of the same drill. Fig. 5 is a view from above of the parts shown in Fig. 1. The V-shaped groove, yet- 2 5 to be cut, is represented by dotted lines. Th

projected alignments of fracture are also represented by dotted lines.

It is known, previous to the making of this present improvement, that straight lines of fracture may be produced in blasting rock by certain shapes of the blast-holes. This present improvement is an improved means and method for blasting out the corner of a piece of rock. Before the drill that is herein shown and described is used, a round hole is drilled at the point where the corner is to be located. Then the said drill is made use of.

The letter a denotes the body of the drill, which is shown as rectangular in cross-section,

and this drill-body is smaller in all of its diameters than the'diameter of the previouslydrilled round hole. This drill-body has an expanded foot, b, which is mainly round on the periphery, this round part fitting, in a general way, to the round shape of the previouslydrilled round hole. This expanded foot I) is not round throughout the entirety of the circle, being broken by the lateral V-shaped cutting-wing c, which cuts the V-shaped groove vertically in the wall of the previously-drilled round hole, the round part of the expanded Serial No. 208,727. (No model.)

foot fitting meanwhile, in a general way, as already described, against the round wall of the hole, and thereby laterally supporting the lower end of the drill as it cuts the V-shap'ed 5 groove in its descent.

The body of the drill is made square, that it may be guided by the guide-plate, as set forth and described in anotherapplication for Letters Patent, the filing of which is of even date with the filing of the application for these present Letters Patent. The previously-drilled round hole is denoted by the letter d, and after it is drilled a vertical V-shaped groove is cut in one wall, as represented in Figs. 1 and 5. Then with the same drill another vertical V- shaped groove is cut in the wall of the round hole at a location such as is indicated by dotted lines in Fig. 5, provided the sides of the stone to be blasted out are to be at right angles to each other. If this angle is to be acute or obtuse, then of course the second V-shaped groove is correspondingly located. After the /two V-shaped grooves have been thus cut in the wall of the round hole a blast is exploded in the hole in any proper manner, and the result will be a substantially perfect corner in the rock which is blasted out. Of course the alignment of the fracture along the sides of the rock is otherwise properly provided for, such provision not forming the subject-matter of this present Letters Patent.

The said other application for Letters Pattent, the filing of which is of even date with the filing of the application for these Letters Patent, is the application of Thomas Murdock, aforesaid, for patent on rock-drilling devices, filed July 22, 1886, Serial No. 208,726; and what is described and claimed in the said application of Thomas Murdock is not claimed as the joint invention of these present applicants.

We have been made aware of the contents of Letters Patent to J. N. VVhartnaby for rockdrill, No. 94,854, dated September 14, 1869, and of the contents of Letters Patent to W. H. Silsby for rock-drill, No. 256,749, dated April 18, 1882, and no claim is made herein to what is described and claimed in the two Letters Patent last mentioned.

We claim as our improvement 1. A drill-body of less diameter than its lower working end, provided at that lower e esvyveo cutting-Wing cutting a V-shaped groove in the Wall of the hole; third, with a like drill cutting a like groove less than half the circle distant from the first groove, and, fourth, ex-

ploding a blast in the hole, all substantially 1 as described, and for the purpose set forth.

THOMAS MURDOOK.

JNO. L. L. KNOX. Witnesses as to Murdock: JAS. G. STRONG, JNo. H. SAGE. Witnesses as to Knox:

JNo. H. KNoX, A. O. AVERILL. 

